1. Field of the Invention
The present invention relates generally to an audio apparatus of a portable terminal. More particularly, the present invention relates to an apparatus and a method for providing a stereo effect when playing an audio file in the portable terminal.
2. Description of the Related Art
Recently, portable terminals have become necessary accessories in the modern life and are widely used by people of all ages. Because of their widespread use, service providers and terminal manufacturers are competing in product (or service) development for product differentiation.
For example, the portable terminal is evolving into a multimedia device and providing various additional functions such as a phone book, games, a short message service, an e-mail service, a morning call service, a digital camera, and a wireless Internet service.
In response to the multimedia trend, portable terminals that are capable of playing music files have been developed and are currently on the market. The portable terminal capable of playing music files enables the user to listen to the music using the portable terminal alone, without a multimedia player such as a conventional MP3 player. On account of its convenience, the use of such a portable terminal is increasing among users and especially in the youth market.
Further, portable terminals are being produced and are coming into the market having an equalizer function and a stereo audio file play function for providing the music in accordance with a user's inclination. That is, the equalizer and audio file play functions allow a user to regulate a particular frequency of low sound, middle sound, and high sound based on the music genre (e.g. rock, classic, ballad, jazz, dance, etc).
To enhance the stereo effect, the stereo audio file play function uses a Left (L) component and a Right (R) component as two input signals and outputs a L+R sum signal, a L component, and a R component. Alternatively, the stereo audio file play function uses the L and R stereo components as two input signals and outputs the L component and the R component at a proper angle using a Head Related Transfer Function (HRTF).
When using the L and R stereo components as the two input signals and outputting the L+R sum signal, the L component, and the R component, the stereo effect enhancement method does not utilize the HRTF and thus has a less complicated implementation because it requires fewer computations. However, this method does not consider the head and the pinna used by the human to locate the sound resource and thus cannot exhibit a notable performance.
Further, since the delay of the L signal and the R signal is combined with the other signals, the L signal may include the R component and the R signal may include the L component. Accordingly, the stereo effect is likely to deteriorate.
The alternative method uses the L and R stereo components as the two input signals and outputs the L component and the R component at a proper angle using the HRTF. However, this process merely divides the L signal and the R signal. As a result, the stereo effect is lessened in simultaneously processing the mono component of the L signal and the R signal. Accordingly, there is a need for an apparatus and a method that provides an improved stereo effect in a portable terminal.